Organocatalytic enantioselective desymmetrisation

Abstract

Organocatalytic enantioselective desymmetrisation of achiral or meso compounds is a powerful strategy for the construction of enantiomerically enriched complex molecules, often with multiple stereocentres and in high selectivities. Recent years have seen increasing use of organocatalysts in desymmetrisation methodology, in contrast to traditional metal- or enzyme-catalysed reactions, with many impressive advances made in the current decade. This review will provide an overview of the field since 2010, with the aim of highlighting both the practical applications and elegance of enantioselective desymmetrisation to the wider synthetic community.

Highly Enantioselective Oxidation of Nonactivated Aliphatic C–H Bonds with Hydrogen Peroxide Catalyzed by Manganese Complexes

“…Since secondary alcohols are rapidly oxidized by these catalysts to the corresponding achiral ketones, 34 we explored the C–H oxidation of substrates that will result in an asymmetric desymmetrization. 35 Parent manganese complexes have recently shown excellent catalytic activity in related aliphatic C–H oxidation reactions, 36,37 and consequently, they were also included in the study. In particular chiral iron and manganese tetradentate complexes of general formula [M(CF 3 SO 3 ) 2 (L)] (L = mcp, and pdp, mcp = N,N ′-dimethyl N,N ′-bis(2-pyridylmethyl)-1,2- trans -diamino cyclohexane, pdp = N,N′ -bis(2-pyridylmethyl)-2,2′-bipyrrolidine, Scheme 2, complexes Fe(mcp) , Fe(pdp) , Mn(mcp) , and Mn(pdp) , respectively) 32,33,38,39 were tested as catalysts in the oxidation of tert -butylcyclohexane ( S1 ).…”

Ring‐Opening Regio‐, Diastereo‐, and Enantioselective 1,3‐Chlorochalcogenation of Cyclopropyl Carbaldehydes

“…[12] To test our notion, achiral meso-cyclopropyl carbaldehyde 1a and p-tolylsulfenyl chloride 2a were chosen as substrates for the optimization. [13] As starting point we chose the first generation MacMillan catalyst [14] using different counterions, whichp rovided the desired product, but without any enantioinduction (Table 1, Entries 1and 2).…”

Lewis Acid Catalyzed Enantioselective Desymmetrization of Donor–Acceptor meso‐Diaminocyclopropanes

“…Donor-acceptor cyclopropanes are often chiral themselves, leading to two possible scenarios:k inetic resolution or ad ynamic kinetic asymmetric transformation (DYKAT). [3] We therefore designed the novel meso-diaminocyclopropane 2 (Scheme 1B). [2i] However, amajor drawback of DY KATprocesses lies in their complex reaction mechanism, requiring both efficient facial selection and control over racemization.…”